In certain known types of motion picture cameras, an exposure metering device is provided, whose light sensitive element receives light coming through the camera lens by means of a reflecting surface arranged on the shutter. In this connection, the expressions "metering device" and "metering means" are intended to be interpreted in a broad sense, including devices which merely give an indication of the correct exposure without actually adjusting or controlling the exposure, and also devices which actually adjust or control the exposure, without necessarily giving a visible indication of the correct exposure or its numerical value.
It is desirable to provide the light sensitive element or photoelectric element of the exposure metering means with the same amount of light (for a given brightness of scene) at regular intervals, regardless of whether the shutter is rotating or is stationary. In known cameras of this type, the means for providing the photoelectric element with the same quantity of light consists, for example, in providing a frosted reflecting surface on that portion of the shutter which is located behind the lens, in the stationary state of the shutter. By this means, the light intensity measured behind the lens is reduced, when the shutter is stationary, by an amount corresponding to the recess on the rotating reflecting surface. It is very difficult to bring about an accurate behavior of the frosted surface so that it is always the same in different cameras being constructed in sequence. Moreover, there is usually a certain range of tolerance in the light sensitive elements installed in the cameras. Therefore, an accurate setting of the exposure metering means is very difficult to achieve, to obtain uniformity in both the rotating and the stationary positions of the shutter, and a relatively wide tolerance has had to be accepted, in the past, within the production run of manufacturing a quantity of theoretically identical cameras.
The object of the present invention, therefore, is to provide a camera of this type with means for delivering the same amount of light to the light sensitive element at regular intervals, with the shutter rotating and with the shutter stationary.
Another object is to provide for a simple calibration adjustment capable of being made easily during the assembly of the camera, to set the exposure metering means accurately, thus compensating for the inevitable tolerances of the constructional elements.